set using alternative hash function?

Austin Bingham austin.bingham at gmail.com
Thu Oct 15 13:24:53 CEST 2009


If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements. Is there a
standard way to have set use a different function? Say I've got a
collection of objects with names. I'd like to create a set of these
objects where the hashing is done on these names. Using the __hash__
function seems inelegant because it means I have to settle on one type
of hashing for these objects all of the time, i.e. I can't create a
set of them based on a different uniqueness criteria later. I'd like
to create a set instance that uses, say, 'hash(x.name)' rather than
'hash(x)'.

Is this possible? Am I just thinking about this problem the wrong way?
Admittedly, I'm coming at this from a C++/STL perspective, so perhaps
I'm just missing the obvious. Thanks for any help on this.

Austin Bingham



More information about the Python-list mailing list